(1) Field of the Invention
The present invention relates to a polymer composition comprising a blockcopolyetherester elastomer. More particularly the present invention relates to a polymer composition comprising a blockcopolyetherester and a specific stabilizer, which affords an extremely improved resistance to thermal exposure.
(2) Description of the Prior Art
It is well known that a blockcopolyetherester composed of polyether soft segments and polyester hard segments shows elastomeric properties and is suitable for fibers, films and molding articles. A blockcopolyetherester, however, contains polyether segments, which are subject to oxidative decomposition followed by coloring and decrease of mechanical properties. Especially the oxidative degradation is accellerated by UV-irradiation or thermal exposure. Therefore utilization of blockcopolyetherester is restricted to some extent.
In order to improve these defects of a blockcopolyetherester, incorporation of various stabilizers have been proposed, but no sufficiently effective stabilizer has been discovered. Although hindered phenols can be considered one of the most economically successful of the known stabilizers for blockcopolyetheresters, they tend to migrate to the surface of molded articles, and thereby the stabilization effects are gradually decreased. Aromatic amines having a more improved stabilization effect make the polymer stain.
Thus, an object of the present invention is to provide a specifically stabilized blockcopolyetherester using a stabilizer which does not cause migration to the surface and discoloring.